Researches in Physical Astronomy. [Abstract]

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15

are now necessary. This construction will also be attended with
the advantage of requiring a much smaller thickness in the plate-
glass, and will thus facilitate the selection of proper pieces of glass
for being worked into an object lens.

From all these considerations, the author entertains the confi-
dent expectation of being able, with proper assistance, to construct
a telescope of two feet aperture and 24 feet in length, which
would as much exceed the most powerful telescopes of the present
day, as these exceed the refractors which existed at the close of the
last century.

December 16.
His Royal Highness the Duke of SUSSEX, President, in the Chair.
The following Presents were received,and thanks ordered for them: —

Illustrations of Mr. S. Cooper's Surgical Dictionary. Published
Monthly. Each Part containing four Lithographic Plates, with
Letter-press descriptions, and references to the Text. Parts 1-3.
8vo. — Presented by the Author.

Occupations of Fixed Stars by the Moon in November and Decem-
ber. 1830. Computed for Greenwich, by Thomas Henderson,
Esq. — The Astronomical Society.

The Geographical System of Herodotus examined and explained,
by a comparison with those of other ancient Authors, and with
modern Geography. With Dissertations on the Itinerary Stade
of the Greeks, the Expedition of Darius Hystaspes, the position
and remains of ancient Babylon, the alluvions of the Nile, and
Canals of Suez ; the Oasis and Temple of Jupiter Ainmon, the
ancient circumnavigation of Africa, and other subjects of History
and Geography. 2nd Edition, revised. By James Rennell, Esq.
F.R.S. 8vo.— "Mrs. Rodd.

Elements of the Economy of Nature, or the Principles of Physics,
Chemistry, and Physiology; founded on the recently discovered
Phenomena of Light, Electro-Magnetism, and Atomic Chemistry.
By J. G. Macvicar, M.A. 8vo. — The Author.

Illustrations of the atmospherical Origin of Epidemic Diseases. 2nd
Edition. By T. Forster, M.B. 8vo. — The Author.

Observations on the Union which has become necessary between the
hitherto separated branches of the Medical Profession, and on
the Foundation of a Faculty of Medicine. By T. Forster, M.B.
8vo The Author.

On the Glanders in the Human Subject. By John Elliotson, M.D.
F.R.S. 8vo The Author.

Science without a Head ; or the Royal Society dissected. By one
of the 687 F.R.S. sss. 8vo.— The Author.

Berliner Astronomisches Jahrbuch fur 1832. Mit Genehmaltung
der Koniglichen Academie der Wissenschaften, herausgegeben
von J. F. Encke, Konigl. Astronom. 8vo. — Professor Encke, For.
Mem. R.S.

16

Verzeichniss dcr von Bradley, Piazzi, Lalandc und Bcssel beobach-
teten Sterne, in dem Theilc des Himmels zwischen I4 h 56°bis
IP 1 ' 4' gerader Aufstcigung, und 15° siidlichcr bis 1;J° nordlichcr
Abweichung, bercchnet und auf 1800 rcdueirt von Hcrrn Pro-
fessor Harding in Gottingen. — Auf Veranlassung der Konigl. Aka-
deraie der Wissenschaften in Berlin. — Akademische Sternkarten :
Zone xvuhr, Blatt 16. folio. — Professor Harding, For. Mem. R.S.

Chart illustrative of the preceding Work. — The Same.

Traitd EUSmentaire de Madere M£dicale. TroisiSme Edition, revue,
corrige'e, et augmented. Par J. B. G. Barbier, D.M. 8vo. — The
Author.

Apercu du Commerce Francais avec tous les Pays du Monde. Par
Cesar Moreau, F.R.S.— The Author.

Eloge Historique de M. le Marquis De la Place, prononce" dans la
Stance publique de l'Academie Royale des Sciences, le 15 Juin
1829 ; par M. le Baron Fourier. 4to — The Academy.

A Paper was read, entitled, " Researches in Physical Astrono-
my;" by John William Lubbock, Esq. V.P. and Treasurer of the
Royal Society.

The author has shown in a former paper, published in the last
part of the Philosophical Transactions for 1830, that the stability
of a system of bodies subject to the law of gravitation, is always
preserved, provided they move in a space absolutely devoid of re-
sistance. This conclusion results from the analytical expressions
for the variations of the elliptic constants in the theory of the
Planetary Motions.

In the present paper he extends his researches to the problem of
the precession of the Equinoxes, which admits of a similar solution
to the former. Of the six constants which determine the position
of the revolving body, and the axis of instantaneous rotation, at any
instant, three have only periodic inequalities ; while the other three
have each a term which varies as the time ; but from the manner in
which these constants enter into the resulting expressions, the equi-
librium of the system may be inferred to be stable, as in the former
case. By the stability of the system, the author wishes to be un-
derstood to mean that the pole of the axis of rotation has always
nearly the same geographical latitude, and that the angular velocity
of rotation, and the obliquity of the ecliptic vary within small limits j
and that its variation is periodical.

The author also gives new methods of obtaining the inequalities
of longitude, and the radius vector, in the planetary theory, retain-
ing the square of the eccentricities. When only the first powers
of the eccentricities are retained, these expressions admit of sim-
plification. He subjoins as a numerical example, the calculation of
the coefficients of two of the inequalities of longitude in the theory
of Jupiter disturbed by Saturn ; and points out the requisite substitu-
tions for rendering the formula? applicable to the case of a superior
planet disturbed by an inferior planet.